Yeah, I've ridden that. There was a route guide in MBR a while back that started and finished in Llangynog and was a big 30+ mile loop clockwise. I took a wrong turn at the top of the bridleway SE out of Llandrillo and ended up riding the bridleway on your link. It was a long slog up and a quick and uneventful loss of height the other side (I rode down the footpath to Tan-y-fedwen to get my ride back on track). To ride from Cadiar Bronwen back to Llandrillo should be fun!

I've ridden up the Wayfarer to Cadair Bronwen and down via Moel Pearce to Llandrillo and then back over the Wayfarer. (Many moons ago.)
Proper wilderness riding and not the best fun in the misty conditions I rode it in. The trail was badly rutted, making it unridable in places and there were deep puddles and huge bogs to contend with.
I imagine on a nice day it would be superb though!

I've been over that before on a Cambrian Challenge ride - we rode/pushed up the foot path then took the BW north west across Moel Pearce before joining the Wayfarer to ride back over to Oswestry.

Can't remember much about the riding - think it was mostly rutted - should be ok in the dry. I do recall hiding in a ditch to fix a puncture as the wind was pretty wild on the tops, and on the way back across the (very wet) Wayfarer we came across an MX bike stuck engine deep in the mud